The present invention relates to a data processing device which is provided with a liquid crystal display having electroluminescent backlighting. Normally, manufacturers are required to design displays as small as possible so that data processing machines may be made more compact. Liquid crystal display devices are available to help realize this goal, but since they cannot illuminate themselves, such displays are usually dark and often indecipherable. There has been proposed a device equipped with an electroluminescent panel to provide the necessary backlighting. However, use at a high level of luminosity considerably shortens the service life of electroluminescent panels.